Introduction to Medical Imaging (5XSA0)

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1 Introduction to Medical Imaging (5XSA) Medical image acquisition and analysis: Endoscopy 1 Endoscopy: Introduction (1) Endo-scopy: looking inside (the body) Minimally invasive procedure. Mostly through natural openings of the body. 2 Fons van der Sommen (f.v.d.sommen@tue.nl) Endoscopy: Introduction (2) 3 Endoscopy: Introduction (3) 4 Specially trained medical staff Patient Endoscopist Types of endoscopic procedures Bronchoscopy (lungs) Colonoscopy (colon) Gastroscopy (stomach & esophagus) Laparoscopy (internal organs) Rhinoscopy (nose) Hysteroscopy (uterus). Endoscopy: Introduction (4) 5 Outline 6 Example: gastroscopy (video) History White light endoscopy Wireless capsule endoscopy Narrow-band imaging Autofluorescence imaging Hyperspectral imaging Medical image analysis in endoscopy Example: cancer detection Summary 1

nl) Endoscopy: Introduction (2) 3 Endoscopy: Introduction (3) 4 Specially trained medical staff Patient Endoscopist Types of endoscopic procedures Bronchoscopy (lungs) Colonoscopy (colon) Gastroscopy

2 History (1) First attempts Bozzini: Lichtleiter (185) / Desormeaux: Endoscope (1853) Light guiding instruments. Utenary tract, rectum, bladder. Early 19s Gastroscope: tube with external light source. Fiberscopes (1) (196s) Capture light through a bundle of flexible glass fibres. Light from an external source through a seperate fiber. 7 History (2) Fiberscopes (2) Use of one fiber and lenses to transfer the image. Videoscopes Connect a camera to the fiberscope. Allows for more persons to look at the body interior. High Definition (HD) endoscopy Allows to detect very subtle changes in tissue White-light endoscopy Light source emits light Reflected by surface tissue Captured by a camera Light source and camera can be at the tip or external Wireless Casule Endoscopy (WCE) Given Imaging () 8-hour journey through the gastro-intestinal tract 2-3 frames/sec 6. images 256 x 256 pixels Narrow-band imaging Shorter wavelengths only penertrate top mucosa Narrow the (sensor) bands to better seperate the layers Narrow-band imaging: examples Kara et al., Gastrointest Endosc. 6 Aug;64(2): Conventional Filter B G R B G R B G R NBI Filter White light Narrow-band imaging White light Narrow-band imaging 2

7 History (2) Fiberscopes (2) Use of one fiber and lenses to transfer the image. Videoscopes Connect a camera to the fiberscope. Allows for more persons to look at the body interior.

3 Autofluorescence imaging When biological structures are exposed to certain wavelengths, they emit light with a spectral signature. Use light sources at these wavelengths and sensors to capture these spectral signatures. Light Induced Fluorescence Endoscopy (LIFE) 13 LIFE: examples 14 Hyper spectral imaging Divide the spectrum in many bands. Create an intensity spectrum for each pixel. See if you can identify spectral signatures. Akbari et al., J. Biomed. Opt. 17(7), 765 (Jul 6, 212). Prostate cancer 15 Goto et al., J. Biomed. Opt. 2(1), 1617 (Jan 2, 215). Gastric cancer Medical image analysis in endoscopy Support the endoscopist Identify tumors / malignant lesions Detect bleeding (remember WCE: 6. images!) Indicate anatomical structures Challenges in endoscopic image analysis Dynamic environment Lighting conditions & Specular reflections Intestinal juices Imaging equipment is limited in size! (Image quality) 16 Medical image analysis in endoscopy Example: Early cancer detection in the esophagus Endoscopists inspects the esophagus System: Suspicious tissue identified 17 = Picture element: pixel 18 3

Light Induced Fluorescence Endoscopy (LIFE) 13 LIFE: examples 14 Hyper spectral imaging Divide the spectrum in many bands. Create an intensity spectrum for each pixel.

4 From literature: Observable difference in color and texture of the surface tissue From literature: Observable difference in color and texture of the surface tissue. Color = pixel values Use the local mean and variance! Texture = local changes in pixel values Use selective filters to find patterns! 2 Early cancer 5 15 Healthy tissue What filter should we use? Good canditate: Gabor filters Orientation Compute the local mean and variance of: Pixel values (color) Filtered pixel values (texture) Scale Color How can we use this for a learning system? After quantification: a set of numbers for each image patch Average color Color variance Average texture Texture variance What numbers indicate early cancer? Early cancer New image patch yields a point Color 23 Classifier: early cancer? = 24 No cancer Texture Dividing line between cancer and no cancer learned from examples. Texture 19 jun

2 Early cancer 5 15 Healthy tissue 5 15 21 22 What filter should we use?

5 25 26 Summary Endoscopy Minimally invasive imaging technique. White-light / Wireless Capsule Endoscopy (WCE). Autofluorescence-, Narrow-band-, Hyperspectral imaging. Endoscopic image analysis Can be of great benifit to the endoscopists. Challenging due to lighting conditions, small-scale technology and dynamic environment. Internships 27 Cancer detection using HD endoscopy Computer-aided diagnosis using OCT imaging 5

Endoscopic image analysis Can be of great benifit to the endoscopists.

Endoscope Optics. Chapter 8. 8.1 Introduction

Endoscope Optics. Chapter 8. 8.1 Introduction Chapter 8 Endoscope Optics Endoscopes are used to observe otherwise inaccessible areas within the human body either noninvasively or minimally invasively. Endoscopes have unparalleled ability to visualize